Membrane valve modulated gas generator

ABSTRACT

A device includes a case having a surface with a perforation and a cavity. A membrane is supported by the case inside the cavity and has an impermeable valve plate positioned proximate the perforation. The membrane is water vapor permeable and gas impermeable and flexes responsive to a difference in pressure between the cavity and outside the cavity to selectively allow water vapor to pass through the perforation into the cavity as a function of the difference in pressure.

BACKGROUND

Some hydrogen generators generate hydrogen by reacting water vapor witha hydride fuel. The water vapor has been provided by different sources,such as ambient, a reservoir of water, or even as a byproduct of achemical reaction such as in the case of fuel cells. When hydrogen isnot required from the hydrogen generator, the supply of water vapor isshut off. The shut off has been accomplished by somewhat complexarrangements of valves.

SUMMARY

A device includes a case having a surface with a perforation and acavity. A membrane is supported by the case inside the cavity and has animpermeable valve plate positioned proximate the perforation. Themembrane is water vapor permeable and gas impermeable and flexesresponsive to a difference in pressure between the cavity and outsidethe cavity to selectively allow water vapor to pass through theperforation into the cavity as a function of the difference in pressure.

A device includes a case having a surface with an array of perforationsand a cavity containing a gas generating fuel. A membrane is supportedby the case inside the cavity, the membrane having an array ofimpermeable valve plates, each positioned proximate a correspondingperforation. The membrane is water vapor permeable and gas impermeableand flexes responsive to a difference in pressure between the cavity andoutside the cavity to move the plate to block the perforations via thevalve plates when the pressure inside the cavity is greater, and tounblock the perforations when the pressure inside the cavity is lowerthan outside the cavity.

A method includes passing water vapor through a gas impermeable, watervapor permeable membrane to a gas producing fuel in a fuel container,responsive to a gas pressure in the container higher than pressureoutside the container, moving a plate supported by the membrane towardsa perforation in the container to impede passing of water vapor to thegas producing fuel, and responsive to a gas pressure in the containerlower than pressure outside the container, moving the membrane and plateaway from the perforation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram cross section representation of a fuelcartridge having a membrane based valve assembly according to an exampleembodiment.

FIG. 2 is a block diagram cross section representation of a portion ofthe fuel cartridge of FIG. 1 showing the valve in an open positionaccording to an example embodiment.

FIG. 3 is a block diagram cross section representation of a portion ofthe fuel cartridge of FIG. 1 showing the valve in a closed positionaccording to an example embodiment.

FIG. 4 is a block diagram cross section representation of an alternativefuel cartridge having a membrane based valve assembly according to anexample embodiment.

FIG. 5 is a top view representation of a membrane having an array ofvalve plates according to an example embodiment.

FIG. 6 is a top view representation of a membrane having an array ofinterconnected valve plates according to an example embodiment.

FIG. 7 is a cross section representation of a power generator utilizinga gas generating cartridge having a membrane based valve assemblyaccording to an example embodiment.

FIG. 8 is a portion of the power generator of FIG. 7.

FIG. 9 is a top view block representation of a manifold for the powergenerator of FIGS. 7 and 8 according to an example embodiment.

FIG. 10 is a cross section representation of a power generatorincorporating a membrane with a valve assembly according to an exampleembodiment.

FIG. 11 is a cross section representation of a portion of the powergenerator of FIG. 10 according to an example embodiment.

FIG. 12 is a cross section representation of a portion of an alternativepower generator according to an example embodiment.

FIG. 13 is a cross section representation of a power generator containerhaving a power generator inserted according to an example embodiment.

FIG. 14 is a graph illustrating water vapor flow rate versus internalpressure of a membrane based valve assembly according to an exampleembodiment.

FIG. 15 is a block diagram of a computer system for implementing acontroller according to an example embodiment.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings that form a part hereof, and in which is shown by way ofillustration specific embodiments which may be practiced. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the invention, and it is to be understood thatother embodiments may be utilized and that structural, logical andelectrical changes may be made without departing from the scope of thepresent invention. The following description of example embodiments is,therefore, not to be taken in a limited sense, and the scope of thepresent invention is defined by the appended claims.

The functions or algorithms described herein may be implemented insoftware or a combination of software and human implemented proceduresin one embodiment. The software may consist of computer executableinstructions stored on computer readable media such as memory or othertype of storage devices. Further, such functions correspond to modules,which are software, hardware, firmware or any combination thereof.Multiple functions may be performed in one or more modules as desired,and the embodiments described are merely examples. The software may beexecuted on a digital signal processor, ASIC, microprocessor, or othertype of processor operating on a computer system, such as a personalcomputer, server or other computer system.

FIG. 1 is a cross sectional representation of a removable fuel cartridge100. Cartridge 100 comprises a case 110 (metal or polymer) containing awater-reactive gas generating fuel 112 in a cavity 113. The cartridge100 may be inserted into a gas consuming device, such as a powergenerator. In one embodiment the power generator comprises a fuel cellsystem and the generated gas comprises hydrogen. A side or face 115 ofthe case 110 is perforated 116, and exposes a selectively permeablemembrane 120 (water vapor permeable, atmospheric gas impermeable) whichseparates the fuel 112 from the ambient environment 122 outside the case110.

In one embodiment, the membrane 120 is positioned between the perforatedface 115 and a permeable plate 125, which may be perforated in oneembodiment. The membrane 120 is flexible, and moves between the plate125 and face 115 responsive to a difference in pressure between thecavity 113 and ambient 122. The plate 125 and face 115 bound themovement of the membrane 120 in one embodiment such that the membrane isnot unduly stressed via the difference in pressure that may develop. Atypical gap may be up to a few hundred micron in some embodiments andmore in others, depending on the lateral dimensions of the membrane. Themembrane may be coupled to sides of the case 110 via adhesive on aperimeter of the membrane or other method to provide a seal that allowsthe difference in pressure to cause the membrane 120 to move transverseto the face 115.

In one embodiment, the membrane 120 comprises one or more valve plates130 that move toward the perforations 116 when the pressure is higherinside the cavity 113, and move away from the perforations when thepressure inside the cavity is lower than ambient 122. In one embodiment,a gasket 135 is formed about the perforations which is compressible toform a seal with corresponding valve plates 130 when the difference inpressure causes the membrane to push the valve plates 130 into contactwith the gasket. The gasket may be optional where the materialscomprising the valve plates 130 and face 115 having perforations 116form an adequate seal when pressed against each other by the differentin pressure. The differences in pressure in some embodiments modulate upto few tenths of a pound per square inch in one embodiment.

In various embodiments, the number of perforations 116 in face 115 mayvary between one and many, forming an array of perforations. Similarly,the number of valve plates may be the same as the number ofperforations, and arranged in an array to mate with each correspondingperforation. In still further embodiments, one or more larger valveplates may be used such that each valve plate may cover multipleperforations.

In one embodiment, a gas permeable particulate filter 140 is positionedbetween fuel 112 and plate 125 to prevent fuel from clogging theperforations in the plate 125. The fuel in various embodiments may beporous to allow the water vapor passing through the perforated face 115,membrane 120 in areas other than those contain the valve plates 130,plate 125, and filter 140 to migrate through the fuel to generate moregas. The fuel porosity in one embodiment varies between approximately15% and 20%. The porosity may be selected to allow adequate movement ofgas and water vapor while at the same time providing a desired gasproducing capability.

The gas also moves through the porous fuel 112 towards a gas exit 145.The gas exit in different embodiments may be positioned on a side of thecase 110 that may be plugged into a gas consuming device. While the gasexit 145 is shown about a middle of the side of the case 115, it may belocated in any convenient location on the case where the gas may beused. A check valve 150 may be coupled to the gas exit and be actuatedby plugging the fuel container 100 into the gas consuming device. Instill a further embodiment, a particulate filter 155 may be positionedabout the check valve 150 and gas exit 145 to prevent the gas exit 145from being clogged by fuel. Channels may be formed within cavity 113 tofacilitate distribution of water vapor and generated gas in stillfurther embodiments.

FIGS. 2 and 3 are partial cross sections illustrating the interaction ofthe valve plates 130 with the perforated plate 115. At 200 in FIG. 2,when a low pressure occurs in chamber 113 due to gas being drawn out ofthe chamber for use, the resulting difference in pressure results in themembrane 120 being flexed toward the plate 125, allowing water vapor toenter through perforations 116, and pass through the membrane 120 atportions of the membrane not being covered by valve plates 130.

FIG. 3 illustrates the interaction of the valve plates 130 with theperforated plate 115 when the pressure inside the chamber 113 is greaterthan ambient 116 pressure. The membrane is shown as being pushed towardthe perforated plate 115, causing the valve plates 130 to come intocontact with the perforated plate 115, optionally via the gasket 135. Asseen, the valve plates 130 are sized to be a little bit larger than theperforations 116 such that they serve to block flow of water vapor whencontacting the perforations 116. When generated gas is drawn out via gasexit 145, the pressure decreases, allowing the valve plates to move awayfrom the perforations 116 and once again allow water vapor to reach thefuel 112 through membrane 120. The flexible membrane with valve platesthus serves to regulate the water vapor flow and hence gas generationresponse to the difference in pressure.

In one embodiment, the water vapor reacts with the fuel 112 to generatehydrogen. The hydrogen is provided via gas exit 145 when the cartridge100 is inserted into a fuel cell based power generator. The powergenerator may also cause the check valve 150 to be opened when thecartridge is inserted, allowing the hydrogen to exit.

FIG. 4 is a cross section of an alternative gas generating cartridge400. Cartridge 400 also contains a water vapor membrane based valvearrangement as shown in FIG. 1 which is numbered consistently withFIG. 1. In addition, a second water vapor membrane based valvearrangement is illustrated on a further side of the cartridge 400. Aside or face 160 is perforated as indicated at 165. Similarly to face115, a gasket 170 may also be used, a similar membrane 175 may bepositioned with valve plates 180 between the face 160 and a perforatedplate 185. A particulate filter 190 may also be positioned between thefuel 112 and the perforated plate 185. Each of these elements operatessimilarly to the valve assembly shown on the other or opposite side ofthe case 110. In further embodiments, more than two such assemblies maybe utilized.

FIG. 5 is a top view of a membrane 500 representation. The membrane 500in one embodiment supports an array of water and gas impermeable valveplates 510. The membrane 500 may be formed of Dupont Nafion® material orGore® PRIMEA® membrane material that is metalized to form the plates510. The valve plates may be formed of metal, such as gold, and may bepatterned by deposition or otherwise formed on the membrane 500 in aposition such that they will mate with the perforations in theperforated plate to form the water vapor valve assembly. Othermaterials, such as a polymer or plastic that is impermeable to gas maybe used in further embodiments, and may be deposited, glued, orotherwise supported in position on the membrane 500.

Membrane 500 in one embodiment, where not covered by valve plates asindicated at 520 is water vapor permeable and gas impermeable. Ionomertype membranes may be used in some embodiments. Example membranematerials include Nafion or PRIMEA membranes.

FIG. 6 is a top view of a membrane 600 representation. The membrane 600in one embodiment supports an array of gas impermeable valve plates 610that maybe interconnected by connectors 612 to provide additionalstructural integrity to the membrane as it flexes responsive to thedifference in pressure. A perimeter band 620 may also be formed toprovide additional structural integrity where the membrane 600 isattached to the case of the cartridge. The valve plates, connectors, andband may be formed of metal, such as gold, and may be patterned bydeposition or otherwise formed on the membrane 600 in a position suchthat they will mate with the perforations in the perforated plate toform the water vapor valve assembly. Other materials, such as a polymeror plastic such as Kapton that is impermeable to gas may be used infurther embodiments, and may be deposited, glued, or otherwise supportedin position on the membrane 600. Each of the elements may be formed ofdifferent materials in further embodiments.

Membrane 600 in one embodiment, where not covered by valve plates asindicated at 615 is water vapor permeable and gas impermeable. Ionomertype membranes may be used in some embodiments. Example membranematerials include Nafion or PRIMEA membranes.

FIG. 7 is a cross section representation of a device 700 to utilize agas generating cartridge case 110. FIG. 8 is a blown up view of aportion of the device 700 and has reference numbers consistent withthose used in FIG. 7. In one embodiment, device 700 includes a case 710having a cavity 712 into which the cartridge 100 may be inserted. Case710 may be formed of the same material as the cartridge case 110 in someembodiments, or other material suitably ridged. A gas channel ortransport path 715 formed in the case 710 may extend from the gas exit145 of case 110 and provide generated gas to a manifold 720 havingmultiple openings 722 to allow water vapor to reach case 110 and the gasgenerating fuel 112.

In one embodiment, manifold 720 forms a structural wall of the case 710,and also includes an array of channels 725 to provide gas to a membrane730, such as a fuel cell membrane electrode assembly. In one embodiment,the gas is hydrogen, which is provided to an anode side of the membrane730. The manifold sandwiches the membrane 730 to prevent hydrogen fromleaking around the membrane, and also exposes a cathode side of themembrane to oxygen from ambient via openings 722. Electricity isproduced by the membrane along with water vapor which migrates towardthe cartridge case 110 along with ambient water vapor to reach the fuel112 and produce more hydrogen, as regulated by the membrane valveassembly in case 110 based on the difference in pressure. Theelectricity generated may be provided to an external device, or a devicein which the device 700 is integrated into in further embodiments.

Management electronics 740 may be disposed anywhere in the device 700,and is shown supported by a bottom plate 750 of device 700, which may bea power generator in some embodiments. In one embodiment, managementelectronics 740 is a controller, such as a micro-controller that may beadapted to manage power generation and delivery, including arechargeable battery, battery charging integrated circuit, etc.Electronics 740 may be separable, and alternatively, its functions maybe provided by device such as a mobile device like a smart phone ortouchpad for example.

The manifold 720 in one embodiment is illustrated in a top viewrepresentation in FIG. 9. Openings 722 are shown as round openings inone embodiment, with the channels 725 running between the openings 722and containing fuel cell membranes 730 which may run the length of thechannels 725 in one embodiment. Manifold 720 further includes an exhaustvalve 735 which vents gas to ambient. The exhaust valve 735 may besolenoid controlled in one embodiment and may be used to exhaustnitrogen and other gases that may build up during operation. Exhaustvalve 735 may also be actuated as a function of pressure, temperature orother sensed parameter or parameters in further embodiments. Also shownis check valve 150 from the case 110.

The device 700 in one embodiment contains a check-valve and fuelcartridge interface 755 which automatically opens the check valve 150when the cartridge case 110 is inserted into the device cavity 712,allowing hydrogen to flow from the cartridge case 110 to the fuel cells730. In some embodiments, multiple valves may be provided on thecartridge case 110 with the device 700 having multiple interfaces 755.

Device 700 in one embodiment is a fuel cell based power generator thatutilizes hydrogen produced from a water reactive hydrogen generatingfuel such as a hydride fuel. Production of hydrogen increases pressurein the case 110 while drawing hydrogen from the case reduces thepressure. When power is not drawn from the fuel cells, hydrogen is notdrawn from the case 110 and the pressure inside the case increases aswater vapor remaining in the case is used to create more hydrogen. Theincreased pressure pushes the membrane supported valve plates into aclosed position with respect to the perforations, shutting off thesupply of water vapor and leading to a decrease or cessation of hydrogenproduction. When power demands increase, the pressure is reduced,resulting in more water vapor being provided to the fuel 112 and theproduction of more hydrogen to provide to the fuel cells. An equilibriumpressure may be established dependent on the electrical load and ambienttemperature and humidity.

In one embodiment, the manifold 720 is generally planar in shape and mayconsist of multiple cells connected in series. The power managementelectronics 740 may include a rechargeable battery, such as a Li-ionbattery manufactured by Saft America Inc. The battery may be used topower the electronics and may also provide additional power duringperiods of high demand or transient fluctuations in power demand. Thebattery may be recharged utilizing electricity generated by the fuelcell. Other rechargeable or non-rechargeable batteries may be used infurther embodiments. One or more sensors 760 may be included at variousportions of the device 700 and coupled to the electronics 740 to providetemperature and/or pressure information for use in controlling variousfeatures, such as exhaust valve 735. A single sensor 760 is shown inblock form in transport path 715 as an example of the one or moresensors. In further embodiments, the number and placement of sensors mayvary as desired. In some embodiments the sensor 760 includes a least oneof a temperature sensor pressure sensor, humidity sensor, and voltagesensor

The fuel 112 may be formed of many different hydrides such ascombinations of chemical hydrides, and combinations of chemical hydridesand metal hydrides may be used for the hydrogen producing fuel, such asfor example alane AlH₃, LiAlH₄, NaAlH₄, KAlH₄, MgAlH₄, CaH₂, LiBH₄,NaBH₄, LiH, MgH₂, Li₃Al₂, CaAl₂H₈, Mg₂Al₃, alkali metals, alkaline earthmetals, alkali metal silicides, or any combinations thereof that act asa water-reactive hydrogen-producing material that reacts with watervapor to produce hydrogen.

In one embodiment, the hydrogen producing fuel may be formed as pelletswith a controlled porosity. The term pellet, is used in a broad sense todescribe any shape or configuration of the hydride particles that occupyin the space allotted to the chemical hydride in the fuel source. Thus,the shape of the chemical hydride pellet is not critical. It may be a,layer, disk, tablet, sphere, or have no specific shape. The shape of thechemical hydride particles may be determined by the shape of the fuelsource and the need to make the most efficient use of the space allottedto the chemical hydride. If appropriate, differently shaped chemicalhydride pellets can be used within one fuel source.

The power generator may be formed in the size of a standard “AA”, “AAA”,“C”, or “D” cell (or any other battery size) that can be removed andreplaced. In further embodiments, the power generator may be positionedwithin a device to be powered in a manner that allows access to the fuelcontainer to remove and replace it with a new or recharged fuelcontainer and also allows access to ambient for providing oxygen to thefuel cell. In one embodiment, manifold 720 may be covered with a waterresistant membrane 770, such as a Gortex® membrane to prevent damage tothe device 700 if it is exposed to liquid water. Such a membrane mayalso be used in other embodiments.

FIG. 10 is a block cross section view of a fuel cell based powergenerator 1000. FIG. 11 is a blown up portion of the generator withnumbering consistent with FIG. 10. In one embodiment, the powergenerator 1000 is formed with a self-modulated fuel container similar tothat illustrated in FIG. 1. In one embodiment, generator 1000 comprisesa case 1010 (metal or polymer) containing a water-reactive gasgenerating fuel 1012 in a cavity 1013. A side or face 1015 of the case1010 is perforated 1016, and exposes a selectively permeable membrane1020 (water vapor permeable, gas impermeable) which separates the fuel1012 from the ambient environment 1022 outside the case 1010.

In one embodiment, the membrane 1020 is positioned between theperforated face 1015 and a perforated plate 1025. The membrane 1020 isflexible, and moves between the plate 1025 and face 1015 responsive to adifference in pressure between the cavity 1013 and ambient 1022. Theplate 1025 and face 1015 bound the movement of the membrane 1020 in oneembodiment such that the membrane is not unduly stressed via thedifference in pressure that may develop. The membrane may be coupled tosides of the case 1010 via adhesive on a perimeter of the membrane orother method to provide a seal that allows the difference in pressure tocause the membrane 1020 to move transverse to the face 1015.

In one embodiment, the membrane 1020 comprises one or more valve plates1030 that move toward the perforations 1016 when the pressure is higherinside the cavity 1013, and move away from the perforations when thepressure inside the cavity is lower than ambient 1022. In oneembodiment, a gasket 1035 is formed about the perforations to form aseal with corresponding valve plates 1030 when the difference inpressure causes the membrane to push the valve plates 1030 into contactwith the gasket. The gasket may be optional where the materialscomprising the valve plates 1030 and face 1015 having perforations 1016form an adequate seal when pressed against each other by the differentin pressure. The differences in pressure in some embodiments modulate upto few tenths of a pound per square inch in one embodiment.

In various embodiments, the number of perforations 1016 in face 1015 mayvary between one and many, forming an array of perforations. Similarly,the number of valve plates may be the same as the number ofperforations, and arranged in an array to mate with each correspondingperforation. In still further embodiments, one or more larger valveplates may be used such that each valve plate may cover multipleperforations.

In one embodiment, a gas permeable particulate filter 1040 is positionedbetween fuel 1012 and plate 1025 to prevent fuel from clogging theperforations in the plate 1025. The fuel in various embodiments may beporous to allow the water vapor passing through the perforated face1015, membrane 1020 in areas other than those contain the valve plates1030, plate 1025, and filter 1040 to migrate through the fuel togenerate more gas. The fuel porosity in one embodiment varies betweenapproximately 15% and 20%. The porosity may be selected to allowadequate movement of gas and water vapor while at the same timeproviding a desired gas producing capability.

In one embodiment, a fuel cell proton exchange membrane (PEM) 1050 issupported by a further face 1060 of the power generator 1000. Face 1060has perforations or holes that allow the hydrogen to migrate to the fuelcell 1050. The fuel cell 1050 receives hydrogen generated by fuel 1012at an anode side facing the fuel 1012, generates electricity, andexhausts water vapor resulting from the reaction to ambient. A cathodeside of the fuel cell 1050 is facing ambient and receive oxygen fromambient.

In one embodiment, the fuel cell 1050 is sandwiched between rigid plates1060 that have holes to allow oxygen and water vapor to pass to and fromthe fuel cell. The holes may or may not line up with the face 1055perforations. A particulate filter 1070 may also be provided between theface 1055 and the fuel 1012 to prevent clogging of the perforations byloose fuel. The fuel cell membrane may be sealed at the sides of thecase to prevent ambient water vapor from reaching the fuel from the fuelcell side of the power generator.

Power generator 1000 in one embodiment integrates the membrane valve,fuel cartridge and fuel cell into one monolithic unit. In such a unit,there is no need for gas seals or routing channels to couple thehydrogen generator to the fuel cell, dramatically simplifying the designof a power generator. Control electronics may also be integrated orseparate.

FIG. 12 is a block diagram of an alternative fuel cell based powergenerator 1200 utilizing a membrane 1210 based valve plate 1212arrangement to control water vapor provided to fuel responsive topressure. A power generator 1200 case 1215 has a chamber 1220 defined bya bottom side 1225 that holds hydrogen producing fuel 1227. A top side1230 of case 1215 is permeable to gas and water vapor, and may alsocontain a liquid water impermeable membrane 1235. The top side 1230 maybe perforated or otherwise permeable in various embodiments.

Membrane 1210 is disposed inside case 1215 between the top side 1230 andthe fuel 1227, which may optionally have a particulate filter 1240positioned to prevent migration of fuel toward membrane 1210. Membrane1210 is sandwiched between two structural support layers 1245 and 1250that provide different functions for different parts of membrane 1210.Support layer 1250 positioned between the membrane 1210 and fuel 1227and is permeable to both water vapor and hydrogen. One portion ofsupport layer 1245 forms a chamber 1255 with an opening 1260 that isexposed to water vapor migrating through top side 1230. A first membraneportion 1265 of the membrane 1210 is disposed within the chamber 1255and includes the valve plate 1212 that moves with the membraneresponsive to pressure to engage with the opening 1260 and prevent watervapor from passing to the fuel 1227 when the pressure in the fuelchamber 1220 is higher than ambient. A gasket 1267 may be disposed onlayer 1245 about the opening 1260 to engage the valve plate 1212 as itmoves to restrict water vapor flow through opening 1260.

A second membrane portion 1270 is patterned with anode and cathodecatalysts, and acts as a membrane electrode assembly fuel cell membrane.Second membrane portion 1270 is positioned between support layer 1245 inan area where the support layers are permeable to water vapor andoxygen. Current collectors 1275 are shown contacting the second membraneportion 1270 to act as anode and cathode contacts. The currentcollectors 1275 may be patterned as conductive traces. In someembodiments, multiple chambers 1255 with membrane portions containingvalve plates and second membrane portions form an array of valves andfuel cell membranes along a length and width of the membrane 1210. Insome embodiments, control electronics may also be integrated orseparate.

FIG. 13 is a block cross section of a power generator container 1300having a replaceable power generator 1200 inserted into a powergenerator container cavity 1310, filling up the cavity in oneembodiment. The power generator container 1300 contains a first sidewall 1315 that is permeable to water vapor, and a gas permeable, liquidwater impermeable membrane 1320 covering the wall to preventparticulates and liquid water from entering the generator 1200 andpossibly reaching fuel 1227. A back side 1325 is shown opposite anopening of cavity 1310, and provides a stop when sliding the powergenerator 1200 into the cavity 1310. No additional gas paths are neededin this embodiment, as power generator 1200 provides hydrogen directlyto fuel cell 1270. In one embodiment, control electronics 1330 areprovided as previously described to both couple to electrodes of fuelcell 1270 for power transfer and potential storage. Container 1300 mayalso contain conductors between the control electronics 1330 and aconnector 1350 on the power generator 1200 that mates with a matingconnector 1355 on the power generator container 1300 when the powergenerator 1200 is plugged into the cavity 1310.

FIG. 14 is a graph 1400 illustrating a proof of concept of a membranewith valve plate assembly according to an example embodiment. Watervapor flow rate in mol/second is shown on a y-axis, with internalpressure shown on an x-axis. A curve 1410 is annotated with thecorresponding position of the valve. External pressure is atmosphericpressure, which appears to be just less than 15 psi. The valve appearsto be open at a little less than 15 psi, and closed at 15 psi andgreater. Note that some minimal flow still occurs when the valve isclosed.

FIG. 15 is a block schematic diagram of a computer system 1500 toimplement control electronics according to an example embodiment. Thecomputer system 1500 may also take the form of an integrated circuit orcommercially available microprocessor or microcontroller having fewercomponents than shown in FIG. 15. One example computing device in theform of a computer 1500, may include a processing unit 1502, memory1503, removable storage 1510, and non-removable storage 1512. Memory1503 may include volatile memory 1514 and non-volatile memory 1508.Computer 1500 may include—or have access to a computing environment thatincludes—a variety of computer-readable media, such as volatile memory1514 and non-volatile memory 1508, removable storage 1510 andnon-removable storage 1512. Computer storage includes random accessmemory (RAM), read only memory (ROM), erasable programmable read-onlymemory (EPROM) & electrically erasable programmable read-only memory(EEPROM), flash memory or other memory technologies, compact discread-only memory (CD ROM), Digital Versatile Disks (DVD) or otheroptical disk storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other medium capableof storing computer-readable instructions. Computer 1500 may include orhave access to a computing environment that includes input 1506, output1504, and a communication connection 1515. The computer may operate in anetworked environment using a communication connection to connect to oneor more remote computers, such as database servers. The remote computermay include a personal computer (PC), server, router, network PC, a peerdevice or other common network node, or the like. The communicationconnection may include a Local Area Network (LAN), a Wide Area Network(WAN) or other networks.

Computer-readable instructions stored on a computer-readable medium areexecutable by the processing unit 1502 of the computer 1500. A harddrive, CD-ROM, and RAM are some examples of articles including anon-transitory computer-readable medium. For example, a computer program1518 capable of providing a generic technique to perform access controlcheck for data access and/or for doing an operation on one of theservers in a component object model (COM) based system may be includedon a CD-ROM and loaded from the CD-ROM to a hard drive. Thecomputer-readable instructions allow computer 1500 to provide genericaccess controls in a COM based computer network system having multipleusers and servers.

The following are sets of examples. Features from the various examplesmay be combined and interchanged in various embodiments. Membrane ValveExamples:

1. A device comprising:

a case having a surface with a perforation and a cavity;

a membrane supported by the case inside the cavity, the membrane havingan impermeable valve plate positioned proximate the perforation, whereinthe membrane is water vapor permeable and gas impermeable and flexesresponsive to a difference in pressure between the cavity and outsidethe cavity to selectively allow water vapor to pass through theperforation into the cavity as a function of the difference in pressure.

2. The device of example 1 and further comprising a gasket positioned tomate between the perforation and the valve plate and form a seal betweenthe valve plate and the perforation when the difference in pressurepushes the membrane and valve plate toward the perforation.

3. The device of any of examples 1-2 wherein the membrane is supportedby the case at a perimeter of the membrane such that water vapor canonly travel through the membrane to reach the cavity containing the gasgenerating fuel.

4. The device of any of examples 1-3 wherein the case further comprisesa gas permeable plate positioned between the membrane and the cavitycontaining a gas generating fuel.

5. The device of example 4 and further comprising a particulate filtersupported by the perforated plate to contain fuel particles within thecavity.

6. The device of any of examples 1-4 wherein the case further comprisesan exit opening for gas generated from a gas generating fuel within thecavity responsive to water vapor.

7. The device of example 6 wherein the exit opening comprises a checkvalve.

8. The device of any of examples 1-7 and further comprising a hydridefuel disposed within the cavity to receive water vapor passed throughthe membrane.

9. The device of any of examples 1-8 wherein the case has an array ofperforations and the membrane has a corresponding array of valve plates.

10. The device of example 9 wherein the array of valve plates areconnected, forming a structurally reinforcing mesh on the membrane.

11. The device of example 10 wherein the mesh further comprises aperimeter band fastened to sides of the case and formed to facilitatemovement of the membrane towards and away from the perforations of thecase.

12. A device comprising:

a case having a surface with an array of perforations and a cavitycontaining a gas generating fuel;

a membrane supported by the case inside the cavity, the membrane havingan array of impermeable valve plates, each positioned proximate acorresponding perforation, wherein the membrane is water vapor permeableand gas impermeable and flexes responsive to a difference in pressurebetween the cavity and outside the cavity to move the plate to block theperforations via the valve plates when the pressure inside the cavity isgreater, and to unblock the perforations when the pressure inside thecavity is lower than outside the cavity.

13. The device of example 12 and further comprising:

a gasket positioned to mate between the perforation and the valve plateand form a seal between the valve plate and the perforation when thedifference in pressure pushes the membrane and valve plate toward theperforation, wherein the membrane is supported by the case at aperimeter of the membrane such that water vapor can only travel throughthe membrane to reach the cavity containing the gas generating fuel;

wherein the case further comprises a perforated plate positioned betweenthe membrane and the cavity containing the gas generating fuel;

a particulate filter supported by the perforated plate to contain fuelparticles within the cavity; and wherein the case further comprises anexit opening for gas generated from the fuel and water vapor.

14. The device of example 13 wherein the gas generating fuel comprises ahydride fuel disposed within the cavity to receive water vapor passedthrough the membrane.

15. The device of example 14 wherein the array of valve plates areconnected, forming a structurally reinforcing mesh on the membrane.

16. The device of example 15 wherein the mesh further comprises aperimeter band fastened to sides of the case and formed to facilitatemovement of the membrane towards and away from the perforations of thecase.

17. A method comprising:

passing water vapor through a gas impermeable, water vapor permeablemembrane to a gas producing fuel in a fuel container;

responsive to a gas pressure in the container higher than pressureoutside the container, moving a plate supported by the membrane towardsa perforation in the container to impede passing of water vapor to thegas producing fuel; and

responsive to a gas pressure in the container lower than pressureoutside the container, moving the membrane and plate away from theperforation.

18. The method of example 17 and further comprising:

producing gas responsive to the water vapor reacting with the fuel inthe container; and

providing the produced gas via a gas exit of the container.

19. The method of any of examples 17-18 wherein the perforationcomprises an array of perforations, and the membrane comprises an arrayof plates corresponding to the array of perforations moving responsiveto gas pressure with the membrane.

20. The method of example 19 wherein the gas producing fuel comprises ahydride that produces hydrogen that is supplied to a fuel cell.

Power Generator Having Hydrogen Manifold Examples:

1. A power generator comprising:

a cavity to accept a hydrogen producing fuel cartridge;

a channel to couple to and receive hydrogen from the fuel cartridge;

a manifold coupled to the channel to receive hydrogen from the channel,the manifold having an opening to receive oxygen and water vapor, themanifold being positioned to provide the water vapor to the cavity;

an array of fuel cell membranes supported by the manifold to receivehydrogen from the manifold and oxygen from the opening in the manifold.

2. The power generator of example 1 and wherein the array of fuel cellmembranes is supported by the manifold in a position to provide watervapor to the cavity.

3. The power generator of any of examples 1-2 and further comprising aprotrusion disposed within the cavity to engage a check valve of thefuel cartridge.

4. The power generator of any of examples 1-3 and further comprising anexhaust valve coupled to the manifold to controllably exhaust gas.

5. The power generator of example 4 and further comprising:

a sensor; and

a controller coupled to the sensor and to the exhaust valve to controlthe exhaust valve responsive to signals from the sensor.

6. The power generator of example 5 wherein the sensor comprises atleast one of a temperature sensor pressure sensor, humidity sensor, andvoltage sensor.

7. The power generator of any of examples 1-6 wherein the manifoldcomprises an array of hydrogen providing channels to distribute hydrogento an anode side of each fuel cell membrane, and second openings toexpose a cathode side of each fuel cell membrane to oxygen provided viathe first openings.

8. The power generator of example 7 and further comprising a hydrogenproducing fuel cartridge disposed within the cavity and coupled to thechannel.

9. The power generator of any of examples 7-8 wherein the manifold has aplanar structure, wherein the first openings comprise an array of airchannels through the manifold, wherein the fuel cell membranes extendalong the hydrogen providing channels separating the hydrogen fromoxygen provided via the first openings, and wherein the manifoldsandwiches the fuel cell membranes between an upper portion containingthe hydrogen providing channels and a lower portion providing access tothe oxygen.

10. The power generator of example 9 and further comprising:

a liquid water impermeable, gas and water vapor permeable membranedisposed between the cathode side of the fuel cell membranes andambient; and

a vent coupled to the manifold to vent gas buildup in the manifold tothe outside of the power generator.

11. A power generator comprising:

a cavity to accept a hydrogen producing fuel cartridge;

a channel to couple to receive hydrogen from the fuel cartridge;

a manifold coupled to the channel to receive hydrogen from the channel,the manifold having an opening to receive oxygen and water vapor, themanifold being positioned to provide the water vapor to the cavity;

an array of fuel cell membranes supported by the manifold to receivehydrogen from the manifold and oxygen from the opening in the manifold,wherein the manifold comprises an array of hydrogen providing channelsto distribute hydrogen to an anode side of each fuel cell membrane, anda second opening to expose a cathode side of each fuel cell membrane tooxygen provided via the first opening;

an exhaust valve coupled to the manifold to controllably exhaust gas;

a sensor; and

a controller coupled to the sensor and to the exhaust valve to controlthe exhaust valve responsive to signals from the sensor.

12. The power generator of example 11 and wherein the array of fuel cellmembranes is supported by the manifold in a position to provide watervapor to the cavity.

13 The power generator of any of examples 11-12 and further comprising aprotrusion disposed within the cavity to engage a check valve of thefuel cartridge.

14. The power generator of example 12 wherein the manifold has a planarstructure, wherein the first opening comprises an array of air channelsthrough the manifold, wherein the fuel cell membranes extend along thehydrogen providing channels separating the hydrogen from oxygen providedvia the array of air channels, and wherein the manifold sandwiches thefuel cell membranes between an upper portion containing the hydrogenproviding channels and a lower portion providing access to the oxygen.

15. The power generator of example 14 and further comprising:

a liquid water impermeable, gas and water vapor permeable membranedisposed between the cathode side of the fuel cell membranes andambient; and

a vent coupled to the manifold to vent gas buildup in the manifold tothe outside of the power generator.

16. A method comprising:

inserting a fuel cartridge into a cavity of a power generator;

receiving hydrogen from the fuel cartridge into a hydrogen channel;

distributing the hydrogen to an anode side of an array of fuel cellmembranes via a manifold having an array of hydrogen channels;

providing oxygen via an opening in the manifold to a cathode side of thearray of fuel cell membranes to produce electricity; and

providing water vapor to the fuel cartridge having a hydride thatproduces hydrogen when exposed to the water vapor.

17. The method of example 16 wherein the water vapor is provided via theopening in the manifold from outside the power generator.

18. The method of any of examples 16-17 wherein the water vapor isprovided via the cathode side of the fuel cell membranes.

19. The method of any of examples 16-18 and further comprisingmodulating the amount of water vapor that reaches the hydride via adifferential pressure responsive water vapor permeable, gas impermeableflexible membrane having a valve plate that mates with an opening in thefuel cartridge.

20. The method of example 19 and further comprising venting excess gasfrom the array of hydrogen channels in the manifold.

Power Generator Having Integrated Membrane Valve Examples:

1. A power generator comprising:

a case having a surface with a perforation and a cavity containing a gasgenerating fuel;

a membrane supported by the case inside the cavity, the membrane havingan impermeable valve plate positioned proximate the perforation, whereinthe membrane is water vapor permeable and gas impermeable and flexesresponsive to a difference in pressure between the cavity and outsidethe cavity to selectively allow water vapor to pass through theperforation to the fuel as a function of the difference in pressure; and

a fuel cell membrane supported by the case and positioned to receivehydrogen at an anode side of the fuel cell membrane and to receiveoxygen from outside the power generator at a cathode side of the fuelcell membrane.

2. The power generator of example 1 and further comprising a firstparticulate filter disposed between the cavity and the membrane.

3. The device of any of examples 1-2 and further comprising a gasketpositioned to mate between the perforation and the valve plate and forma seal between the valve plate and the perforation when the differencein pressure pushes the membrane and valve plate toward the perforation.

4. The device of any of examples 1-3 wherein the membrane is supportedby the case at a perimeter of the membrane such that water vapor canonly travel through the membrane to reach the cavity containing the gasgenerating fuel.

5. The device of any of examples 1-4 wherein the case further comprisesa perforated plate positioned between the membrane and the cavitycontaining the gas generating fuel.

6. The device of example 5 and further comprising a particulate filtersupported by the perforated plate to contain fuel particles within thecavity.

7. The device of any of examples 1-6 and further comprising a waterreactive hydrogen generating fuel disposed within the cavity to receivewater vapor passed through the membrane.

8. The device of any of examples 1-7 wherein the case has an array ofperforations and the membrane has a corresponding array of valve plates.

9. The device of example 8 wherein the array of valve plates areconnected, forming a structurally reinforcing mesh on the membrane.

10. The device of example 1 wherein the membrane comprises a catalystpatterned portion to form the fuel cell membrane.

11. The device of example 10 wherein water vapor produced by the fuelcell membrane is provided back to the fuel via perforation asselectively allowed by the membrane and valve plate.

12. The device of example 1 wherein the membrane and fuel cell membraneare positioned on opposite sides of the fuel.

13. A power generator comprising:

a case having a surface with an array of perforations and a cavitycontaining a gas generating fuel;

a membrane supported at a first side of the case inside the cavity, themembrane having an array of impermeable valve plates, each positionedproximate the perforations, wherein the membrane is water vaporpermeable and gas impermeable and flexes responsive to a difference inpressure between the cavity and outside the cavity to selectively allowwater vapor to pass through the perforations to the fuel as a functionof the difference in pressure; and

a fuel cell membrane supported to receive hydrogen at an anode side ofthe fuel cell membrane and to receive oxygen from outside the powergenerator at a cathode side of the fuel cell membrane.

14. The power generator of example 13 and further comprising:

a first particulate filter disposed between the cavity and the membrane;and a second particulate filter disposed between the cavity and the fuelcell membrane.

15. The power generator of any of examples 13-14 and further comprisingan array of gaskets positioned to mate between the perforations and thevalve plates and form a seal between the valve plates and theperforations when the difference in pressure pushes the membrane andvalve plates toward the perforations.

16. The power generator of any of examples 13-15 wherein the membrane issupported by the case at a perimeter of the membrane such that watervapor can only travel through the membrane to reach the cavitycontaining the gas generating fuel.

17. The power generator of any of examples 13-16 wherein the casefurther comprises a perforated plate positioned between the membrane andthe cavity containing the gas generating fuel, wherein the gasgenerating fuel comprises a hydride fuel.

18. A method comprising:

passing water vapor through a gas impermeable, water vapor permeablemembrane to a gas producing fuel in a power generator;

responsive to a gas pressure in the container higher than pressureoutside the power generator, moving a plate supported by the membranetowards a perforation in the power generator to impede passing of watervapor to the gas producing fuel;

responsive to a gas pressure in the power generator lower than pressureoutside the power generator, moving the membrane and plate away from theperforation;

providing gas produced by the gas producing fuel reacting with the watervapor to a fuel cell membrane; and

providing oxygen to the fuel cell membrane and exhausting water vaporproduced by a reaction between hydrogen and oxygen away from the powergenerator.

19. The method of example 18 wherein the perforation comprises and arrayof perforations, and the membrane comprises an array of platescorresponding to the array of perforations moving responsive to gaspressure with the membrane.

20. The method of example 19 wherein the fuel cell membrane comprisescatalyst coated portions of the membrane.

The invention claimed is:
 1. A device comprising: a case having asurface with a perforation and a cavity; a membrane inside the cavity,the membrane supported by the case, the membrane having an impermeablevalve plate positioned proximate the perforation, wherein the membraneis water vapor permeable and gas impermeable and flexes toward and awayfrom the perforation responsive to a difference in pressure between thecavity and outside the cavity to selectively allow water vapor to passthrough the perforation into the cavity as a function of the differencein pressure.
 2. The device of claim 1 and further comprising a gasketpositioned to mate between the perforation and the valve plate and forma seal between the valve plate and the perforation when the differencein pressure pushes the membrane and valve plate toward the perforation.3. The device of claim 1 wherein the membrane is supported by the caseat a perimeter of the membrane such that water vapor can only travelthrough the membrane to reach the cavity containing a gas generatingfuel.
 4. The device of claim 1 wherein the case further comprises a gaspermeable plate positioned between the membrane and the cavitycontaining the gas generating fuel.
 5. The device of claim 4 and furthercomprising a particulate filter supported by the perforated plate tocontain fuel particles within the cavity.
 6. The device of claim 1wherein the case further comprises an exit opening for gas generatedfrom the gas generating fuel within the cavity responsive to watervapor.
 7. The device of claim 6 wherein the exit opening comprises acheck valve.
 8. The device of claim 1 and further comprising a hydridefuel disposed within the cavity to receive water vapor passed throughthe membrane.
 9. The device of claim 1 wherein the case has an array ofperforations and the membrane has a corresponding array of valve plates.10. The device of claim 9 wherein the array of valve plates areconnected, forming a structurally reinforcing mesh on the membrane. 11.The device of claim 10 wherein the mesh further comprises a perimeterband fastened to sides of the case and formed to facilitate movement ofthe membrane towards and away from the perforations of the case.
 12. Adevice comprising: a case having a surface with an array of perforationsand a cavity containing a gas generating fuel: a membrane inside thecavity, the membrane supported by the case, the membrane having an arrayof impermeable valve plates, each positioned proximate a correspondingperforation, wherein the membrane is water vapor permeable and gasimpermeable and flexes toward and away from the perforation responsiveto a difference in pressure between the cavity and outside the cavity tomove the plate to block the perforations via the valve plates when thepressure inside the cavity is greater, and to unblock the perforationswhen the pressure inside the cavity is lower than outside the cavity.13. The device of claim 12 and further comprising: a gasket positionedto mate between the perforation and the valve plate and form a sealbetween the valve plate and the perforation when the difference inpressure pushes the membrane and valve plate toward the perforation,wherein the membrane is supported by the case at a perimeter of themembrane such that water vapor can only travel through the membrane toreach the cavity containing the gas generating fuel; wherein the casefurther comprises a perforated plate positioned between the membrane andthe cavity containing the gas generating fuel; a particulate filtersupported by the perforated plate to contain fuel particles within thecavity; and wherein the case further comprises an exit opening for gasgenerated from the fuel and water vapor.
 14. The device of claim 13wherein the gas generating fuel comprises a hydride fuel disposed withinthe cavity to receive water vapor passed through the membrane.
 15. Thedevice of claim 14 wherein the array of valve plates are connected,forming a structurally reinforcing mesh on the membrane.
 16. The deviceof claim 15 wherein the mesh further comprises a perimeter band fastenedto sides of the case and formed to facilitate movement of the membranetowards and away from the perforations of the case.